Shift mechanism for typewriters



March 12, 1946. E, RQ 2,396,344

' SHI EFTMECHANISM FOR TYPEWRITERS Filed Nov. 17-, 1944 Patented Mar. 12, 1946 SHIFT MECHANISM FOR TYPEWRITERS Edna G. Robeson, Miami, Fla, assignor of onehalf to Bert Alan Crawford, Miami, Fla.

Application November 1'7, 1944, Serial No. 563,893

4 Claims.

The invention relates to typewriters and has as an object the provision of improved mechanism for shifting of the type bar so as to impress selected type.

It is an object of the invention to provide a shift mechanism for typewriters that will lessen the physical force required to bring about the shifting of type.

It is a further object of the invention to provide a controlled shift thatwill render it unnecessary to lift or lower the basket or carriage of the machine.

It is a further object of the invention to provide a shift mechanism involving the mounting of the type bars upon movable pivots, which movement of the pivots may be brought about by the force utilized to cause the striking of the type against the platen.

It is a further object to provide a type bar shifting mechanism wherein it is only necessary to move a stop member to permit normal force applied to the type bar to also cause the shifting from lower case to upper case type.

Further objects will appear from the following description of an illustrative embodiment of the invention shown in the accompanying drawing,

wherein:

Figure 1 is a detail side elevation of the type bar, the key lever, the shifting mechanism and the platen shown diagrammatically.

Fig. 2 is a view similar to Fig. 1 showing the striking of an upper case letter.

Fig. 3 is a detail vertical section on line 3-3 of Fig. 1.

As shown the key bar is indicated at I showing a key at II which key bar is pivoted upon a fixed pivot at I2. A shift bar I3 is shown having a shift key at I4, the bar shown as pivoted upon a pivot located at I5 intermediate the ends of the shift bar so that the shift bar is substantially balanced about said pivot. The shift bar is shown carrying integrally therewith an upwardly directed portion I6 having its upper end formed. with an upwardly open recess -Il for coaction with a swinging bar 3| extending across the machine, carried by members 32 one at each side of the machine, only one of which is shown, which members 32 are mounted on pivots as 33. The bar 3| is shown as urged to normal position against stop 34 by tension spring 35.

To pivotally support levers I8, there is shown a bar I9 extending across the machine and fixedly mounted at its ends in clips secured by screws to the frame of the machine. The levers I8 are each formed with a recess 36 formed. with a cam surface as at 37. To adjust the coaction of the bar 31 with the individual levers I8 there is shown an adjusting screw 38 for each lever which ride at their ends on the cam surfaces 31 when the bar 3| is moved by the spring or springs 35,

thus holding each lever firmly against the upperstop 22 extending across above all levers I8.

The type bars 23 are shown as each pivoted at 24 upon the forward ends of the levers I8 and normally lying against the bar 33. To actuate the type bars 23 by the key bars I 0, each key bar is shown as connected by a link 25 fro-m pivot 26 to a short projection of the type bar beyond the pivot 24.

The type bar is shown as carrying two type members, a lower case type at 21 and an upper case type at 28.

With the parts shown in the position of Fig. l, a downward pull upon the link 2'5 caused by depression of the key bar ID will produce a downward pull upon the lever I8 and also will cause a quick upward movement of the lever 23 to cause a lower case letter to strike the impact line of the platen. If the lever I8 were free to move during this action, the downward pull of the link 25 would cause the recessed end of lever I8 to rise, whereupon the type bar would assume the position of Fig. 2 and the upper case type would strike the impact line of the platen, but in the position of parts shown in Fig. 1 upward movement of the free end of the lever I8 is prevented by stop screw 38. The portion I6 of the shift bar is held downward in the normal position of Fig. l by means of a tension spring 29 which spring is anchored upon a fixed portion of the typewriter frame and to the upwardly extending portion I3 at its remaining end. It will be seen that the spring 29 could be anchored to the shift bar in any other position which will cause the stop I"! to remain in its normal position of Fig. 1.

The type bar in 'its depressed position lies against a fixed stop 30 and may be normally held in this position by spring mechanism or in any desired manner but the gravity of the bar 23 will tend to retain the type bar in this position so that the spring referred to is only desirable for a return to normal of the type bar and therefore may be relatively light and provide little resistance to be overcome by force applied upon the key II.

When the stop bar 3I is moved to the position of Fig. 2', the initial force applied to the link 25 will first lower the pivot 24 with the lever I8 against the stop 2I in its shifted position, thus causing depression of the movable pivot 24 of the type bar to the position shown in Fig. 2, wherein the distance thereof from the impact line of the platen is increased to such an extent as to cause the upper case letter to strike in the necessary position to impress the upper case letter upon the impact line. It will be understood that stops 2| and 22 are bars extending continuously across the machine in the path of each of the levers l8. The levers it are individual to the type bars. The force to actuate the shift mechanism therefore is fundamentally only the force necessary to extend the springs 29 and 35.

It is important that there be no movement of the pivot 24 while writing lower case letters as such movement would destroy alignment. Therefore, the stops preventing such movement must be in firm contact with the free end of the levers l8. For this purpose the adjustable stop-screws 38 and the cam surfaces 31 are particularly useful.

The shifting from the lower case to upper case letter is therefore automatically caused by the force applied upon the links 25 under control of the stops 38.

The term typewriter as used herein and in the following claims is adopted for convenience as including any machine where characters are mounted on a swinging bar and impressed upon a receiving surface by being moved thereagainst.

The characters may be letters, figures, perforating means or the like. The plurality of type may be upper and lower case forms of the same letter, or maybe different letters or a plurality of different figures.

Minor changes may be made in the physical embodiment of the invention within the scope of the appended claims without departing from the spirit of the invention.

I claim:

1. A type shift for type machines comprising, in combination: a lever pivoted between its ends upon a type machine frame in such a position that motion thereof about its pivot changes the distance of a free end thereof from the impact line of a platen of the machine; a type bar pivoted upon said free end; means to apply force to said type bar to simultaneously cause striking movement of the type bar and tendency to movement of the lever about its pivot; means to control the response of the lever to such tendency, comprising a movable stop in the path of movement of a portion of the lever when the lever is moved by force applied to said type bar.

2. A type shift for type machines comprising, in combination: a lever pivoted between its ends upon a type machine frame in such a position that motion thereof about its pivot changes the distance of a free end thereof from the impact line of a platen of the machine; a type bar pivoted upon said free end; means to apply force to said type bar to simultaneously cause striking movement of the type bar and tendency to movement of the lever about its pivot; means to control the response of the lever to such tendency, comprising a movable stop in the path of movement of a portion of the lever when the lever is moved by force applied to said type bar, and means to position said stop.

3. A type shift for type machines comprising, in combination: stationary pivot means; a plurallty of levers pivoted on said means; a plurality of type bars pivoted between their ends on the respective levers; a plurality of type characters carried by an outer end of each type bar; a link connecting the remaining end of each type barwith a key bar for causing striking movement of the type bars with stress on the lever tending to vary the distance of the type bar pivot from the printing line; movable stop means acting to resist said stress; and means to position said stop means to prevent or permit said variation of distance whereby to effectuate a choice of type to be impressed.

4. The structure of claim 3 wherein the stop means is common to all the pivoted levers.

EDNA G. ROBESON. 

